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feat(toolchain): include err in rustc_version output #4741

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feat(toolchain): include err in rustc_version output #4741

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66 changes: 37 additions & 29 deletions src/toolchain.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -284,47 +284,55 @@ impl<'a> Toolchain<'a> {
#[tracing::instrument(level = "trace")]
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@rami3l rami3l Mar 8, 2026

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Suggest adding some snapshot tests to better demonstrate this new feature.

pub fn rustc_version(&self) -> String {
match self.create_command("rustc") {
Err(e) => format!("(rustc does not exist: {e})"),
Ok(mut cmd) => {
cmd.arg("--version");
cmd.stdin(Stdio::null());
cmd.stdout(Stdio::piped());
cmd.stderr(Stdio::piped());
self.set_ldpath(&mut cmd);

// some toolchains are faulty with some combinations of platforms and
// may fail to launch but also to timely terminate.
// (known cases include Rust 1.3.0 through 1.10.0 in recent macOS Sierra.)
// we guard against such cases by enforcing a reasonable timeout to read.
let mut line1 = None;
if let Ok(mut child) = cmd.spawn() {
let timeout = Duration::new(10, 0);
match child.wait_timeout(timeout) {
Ok(Some(status)) if status.success() => {
let out = child
.stdout
.expect("Child::stdout requested but not present");
let mut line = String::new();
if BufReader::new(out).read_line(&mut line).is_ok() {
let lineend = line.trim_end_matches(&['\r', '\n'][..]).len();
line.truncate(lineend);
line1 = Some(line);
match cmd.spawn() {
Comment on lines 294 to +295
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@rami3l rami3l Mar 8, 2026

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Nit: could try to reduce some rightward drift here and in sections below. Something along the lines of:

let mut child =  match cmd.spawn() {
    Err(e) => return format!("(error reading rustc version: {e})"),
    Ok(child) => child,
};
[..]

Err(e) => {
format!("(error reading rustc version: {e})")
}
// some toolchains are faulty with some combinations of platforms and
// may fail to launch but also to timely terminate.
// (known cases include Rust 1.3.0 through 1.10.0 in recent macOS Sierra.)
// we guard against such cases by enforcing a reasonable timeout to read.
Ok(mut child) => {
let timeout = Duration::new(10, 0);
match child.wait_timeout(timeout) {
Ok(None) => {
let _ = child.kill();
String::from("(timeout reading rustc version)")
}
Err(e) => {
format!("(error reading rustc version: {e})")
}
Ok(Some(status)) => {
if !status.success() {
return format!("(error reading rustc version: {status})");
}

let out = child
.stdout
.expect("Child::stdout requested but not present");
let mut line = String::new();
match BufReader::new(out).read_line(&mut line) {
Ok(_) => {
let lineend =
line.trim_end_matches(&['\r', '\n'][..]).len();
line.truncate(lineend);
line
}
Err(e) => format!("(error reading rustc version: {e})"),
}
}
}
Ok(None) => {
let _ = child.kill();
return String::from("(timeout reading rustc version)");
}
Ok(Some(_)) | Err(_) => {}
}
}

if let Some(line1) = line1 {
line1
} else {
String::from("(error reading rustc version)")
}
}
Err(_) => String::from("(rustc does not exist)"),
}
}

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